High Isolation Contactor with Test Pin and Housing For Integrated Circuit Testing

ABSTRACT

A test socket (14) for a testing an integrated circuit (12) with controlled impedance while maintaining the structural integrity of the test pins (20). The pin (20) can have a sidewall with a thick portion 32 and a thinner portion (30) along the length of the pin. The pin can have projections (42) which provide a standoff from the slot (40). The sidewalls themselves can have projections or lands (60, 61) which extend into the slot and provide stability for the pin (20).

BACKGROUND OF THE INVENTION Field of Invention

This disclosure relates to the field of microcircuit/IC testing devices,more particularly, a test socket for testing integrated circuit chips.

Description of the Related Art

Microcircuits are well known electrical components that combine hundredsor thousands of individual circuit components and connections in a smallvolume. The package that holds a typical microcircuit may be no largerthan 5 mm square by 0.5 mm thick. One common type of container for amicrocircuit called a leadless package, has small connector or contactpads along the periphery of one surface of the package. A single packagemay have several dozen contact pads by which power is supplied to themicrocircuits and signals sent to and from the microcircuit. The contactpads are soldered onto the conductors of a circuit board during assemblyof the electrical device.

Before a microcircuit is soldered onto a circuit board, the microcircuitmust be tested to assure design functionality. Soldering a defectivemicrocircuit onto a circuit board often ruins the entire board, sincetypically it is either not possible or not economic to remove adefective microcircuit from a circuit board. Since typical microcircuitsare the result of a complex manufacturing process, testing is essentialto assure that every microcircuit is completely functional.

For a number of reasons, testing these microcircuits is complex. In thefirst place, one should not solder the microcircuits to be tested intothe test fixture because the act of removing the microcircuits whentesting is complete might itself damage the microcircuit.

Secondly, the microcircuits are small and the contacts are closelyspaced, on perhaps as small as a 0.3 mm pitch or smaller. The contactsthemselves may be as small as 0.05 mm wide for accurate testing; thetest fixture contacts must make reliable, low-resistance contact witheach of the microcircuit contacts during the entire test process, whichmay extend to even many hours. Failure to make proper contact with eachmicrocircuit contact for the entire test sequence results in a test thatincorrectly fails the microcircuit.

While it is important to test each microcircuit thoroughly, it is alsoimportant to test them quickly and cheaply. Accordingly, automatedtesters have been developed that operate with little human interventionto reliably test hundreds or thousands of individual microcircuits perhour.

A typical test contactor (socket) has its own housing with one or morearrays of test contacts that are spaced and aligned to make temporarymechanical contact with the connector pads on the microcircuit package.Each test socket contact is designed to resiliently deflect a very smallamount when force is applied. This accommodates any dimensionalvariations in either the microcircuit package or the test socket.

Some semiconductor devices operate at very high frequencies. In order totest them, higher performance contacts are needed. One method to improvethe performance of a contact is to make it shorter and/or thinner.

When a contact pin gets thinner, it also changes its impedance which inturn changes the high frequency response. A thinner pin will also haveless contact surface on the load board and thus resistance may increase.Thinner contacts also have the disadvantage of being more likely to bendin response to insertion by a robotic inserter/handler. A solution tothese problems is needed.

Reference to U.S. Pat. Nos. 7,737,708, 5,967,848, 6,203,329 and9,274,141 which are incorporated herein by reference as backgroundmaterial.

BRIEF SUMMARY

The following summary is intended to assist the reader in understandingsome aspects of the disclosure. It does not define the scope of theinvention. Please refer to the claims for that.

As IC chips have higher densities, it is necessary to make the testcontactor/housing smaller to accommodate. Test contacts/pins areassembled into a housing/contactor to constrain them in place whentesting an electronic device/IC. Specific changes to the geometry of thecontacts and housing can be made to match the contact impedance to theIntegrated Circuit (IC) impedance. This will reduce signal reflectionswhile preventing a loss of mechanical performance.

This requires the pins and the spacing between the pins to be madelikewise smaller. This creates several negative consequences includingstructurally weaker pins and problems with maintaining desired impedanceof the test fixture due to the loss of dielectric space between pins. Inelectronics, impedance matching is the practice of designing the inputimpedance of an electrical load to maximize power transfer or minimizesignal reflection from the load. Many integrated circuits are designedto have specific input and output impedances when soldered in place inan electronic device. To optimize test results, test equipment shouldalso be constructed to minimize signal reflections and maximize powertransfer.

One solution to the negative effects of a thinner pin is to make onlypart of the pin thinner and having another part wider. Another solutionis to provide projections between the housing pin slot and the pin inorder to stabilize it against bending or flexing laterally duringtesting. An important benefit of such solutions is that they provideadditional dielectric benefits by providing spacing for air, which has avery LOW dielectric constant and allowed for better impedance and highfrequency response. When this pin geometry is combined with a specifichousing geometry, the result is air gaps between the pins. Air has avery low dielectric constant, so these air gaps improve the impedance ofthe pins when compared to the impedance of the same pins with typicalhousing materials between them.

The benefit of the invention allows thicker pins (hence stronger andable to carry more electrical current) that exhibit improved electricalperformance through improved impedance.

Improved contact impedance can be achieved in many ways which aredetailed below. Some examples are to provide an air gap between the pinand the housing holding the pin, but also providing a way to maintainthe pin vertically oriented and providing strength to make up for thelack of solid wall interface of a typical housing which engages the pinsidewalls directly and provides support for the pin against lateraldeflection and bending. The air gap can be created by making one or bothsidewalls of the pin thicker than other parts of the pin. This willresult in some of the pin engaging with the housing sidewall but stillleaving increased air spacing along other parts of the pin. One solutionis to place bumps (projections) on the sidewalls of the pin or the innerwalls of the housing so that the projections provide the desired supportbut leave large air gaps. Note that since the pins are slidable in theslot, the pin is preferably only in slight frictional contact with theslot inner walls. That could also be considered an air gap butinsignificant from an impedance point of view.

Another solution is to thicken part of the pin (or sidewall) but not allof it. One preferred place of thickening is at the base of the pin as itwill reduce the pressure on the load board, which will minimize wear onthe load board pad.

The two solutions can also be achieved simultaneously. For example, bycreating a pin with a thicker portion on one or both sidewalls where thethicker portion traverses the pin adjacent the top to adjacent thebottom. If the pin is “s” shaped, then a serpentine s-shaped sidewallextension will create a stronger pin.

The same result can be achieved by providing projection(s) from thesidewall(s). The projections can be conductive and coated with anon-conductive layer so that the pins do not short to the inner housingwalls, or non-conductive. A configuration like this with non-conductiveprojections can be used to position two pins next to each other (with nohousing webbing/wall in between). The projections are preferablypositioned differently on each side of the pin so that the projectionsdon't touch each other and cause a problem when the contacts areinstalled against each other and then actuated during IC testing. Insuch case, the projections/lands of one pin sidewall are not alignedwith the projections/lands of the adjacent pin sidewall so that the pinsslide by each other but the projection of one pin does not touch orcollide with the projections of the adjacent pin. The elimination of thehousing separation wall between pins will allow tighter pin density andmore dielectric air instead of housing dielectric. The configurationwith non-conductive bumps can also be used with a metal housing forincreased isolation between pins.

The projections can also be conductive with no coating.

Lowering the dielectric constant can be obtained by removing part of thehousing sidewall where it is not needed for structural support. Thisincreases the dielectric air volume between the contact pins.

It is possible to combine ceramics with metalizing. The pin or housingcan be metalized over ceramic or other non-conductors, or reversed themetal layer can be within a sandwich of ceramic.

A preferred solution is that the base or lower portion of the pin isthicker than the upper portion. This provides a larger base for contactwith the load board and also provides greater flexibility in getting adesired impedance match for the pin/housing. It also causes less damageto the load board because the force/unit area is lower. One solution isa stepwise change in the pin thickness and having a ledge where thechangeover occurs. It could also be a smooth transition in thicknessfrom one end to the other.

The disclosure provides full details of the inventive concepts, but thefollowing is a summary to assist the reader.

There is disclosed, an apparatus for electrically connecting a lead ofan integrated circuit (12) device to be tested to a correspondingterminal of a load board (24) at a test site, having any or all of thefollowing elements:

a. a housing (14) having upper and lower surfaces, a first surfaceapproachable by an integrated circuit device under test (12) to betested and a second surface proximate the load board;

b. a slot extending through said housing from the first surface to thesecond surface, said slot including parallel spaced apart opposing firstand second inner walls thereby defining a space between said sidewall;

c. a contact pin (20) having first and second sidewalls and beingslideably receivable in said slot (40), said pin having a first endengageable by the lead and a second end in engagement with the terminal,said pin filling only a portion of said slot thereby leaving a gapbetween said pin sidewalls and said slot inner walls;

d. a first projection (61, 60, 47, 42, 43, 34) filling a portion of saidgap adjacent said first inner wall and a second projection filling aportion of said gap adjacent said second inner wall; said projectionsproviding longitudinal stability for said pin as it is engaged by thedevice under test and allowing air to provide a dielectric around saidprojections in said gap.

There is also disclosed an apparatus wherein said projections extendfrom said pin toward said inner wall.

There is also disclosed an apparatus wherein housing includes tubularelastomeric resilient element and wherein said pin includes an arcuaterecess for receiving a portion of said resilient element and whereinsaid projection extends from said pin sidewalls and encompasses at leasta portion of said resilient element.

There is also disclosed an apparatus wherein said projections are aplurality of lands spaced across the pin sidewall.

There is also disclosed an apparatus wherein said lands areasymmetrically placed on said first side wall relative to said secondsidewall.

There is also disclosed an apparatus wherein said projections are aplurality of lands spaced across the pin inner wall of said slots.

There is also disclosed an apparatus wherein said projections extendfrom said inner walls of said slot toward said pin.

There is also disclosed an apparatus wherein said pin includes a top andbottom ends and wherein said projections extend adjacent said top andbottom ends.

There is also disclosed an apparatus wherein said pin includes a top andbottom ends and wherein said projections extend between said top andbottom ends along a curved path.

There is also disclosed an apparatus wherein said pin includes a top andbottom ends and wherein said projections extend between said top andbottom ends along a curved path and including a land portion partiallysurrounding said resilient member.

There is also disclosed an apparatus wherein said pin includes a top andbottom ends and wherein said projections extend between said top andbottom ends along a diagonal path.

There is also disclosed an apparatus wherein said housing (14) includesa top surface having said slots (40) and wherein said surface adjacentsaid slots is recessed (31) thereby exposing a portion of said pins toair.

There is also disclosed an apparatus for electrically connecting a leadof an integrated circuit (12) device to be tested to a correspondingterminal of a load board (24) at a test site, having any or all of thefollowing elements:

a. a housing (14) having upper and lower surfaces, a first surfaceapproachable by an integrated circuit device under test (12) to betested and a second surface proximate the load board;

b. a slot extending through said housing from the first surface to thesecond surface, said slot including parallel spaced apart opposing firstand second inner walls thereby defining a space between said sidewall;

c. a contact pin (20) having first and second sidewalls and beingslideably receivable in said slot (40), said pin having a first endengageable by the lead and a second end in engagement with the terminal,said pin filling only a portion of said slot thereby leaving a gapbetween said pin sidewalls and said slot inner walls;

d. a first projection (61, 60, 47, 43, 42, 34) filling a portion of saidgap extending from said first inner wall and a second projection fillinga portion of said gap extending from said second inner wall; saidprojections providing longitudinal stability for said pin as it isengaged by the device under test and allowing air to provide adielectric around said projections in said gap.

There is also disclosed an apparatus wherein said projections are landshaving planar distal surfaces.

There is also disclosed an apparatus wherein said projections areconical having planar distal surfaces.

There is also disclosed an apparatus wherein said projections arespherical.

There is also disclosed an apparatus wherein said projections arecylindrical and having planar distal surfaces.

There is also disclosed an apparatus for electrically connecting a leadof an integrated circuit (12) device to be tested to a correspondingterminal of a load board (24) at a test site, having any or all of thefollowing elements:

a. a housing (14) having upper and lower surfaces, a first surfaceapproachable by an integrated circuit device under test (12) to betested and a second surface proximate the load board;

b. a slot extending through said housing from the first surface to thesecond surface, said slot including parallel spaced apart opposing firstand second inner walls thereby defining a space between said sidewall;

c. a contact pin (20) having first and second sidewalls and beingslideably receivable in said slot (40), said pin having a first endengageable by the lead and a second end in engagement with the terminal,said pin filling only a portion of said slot thereby leaving a gapbetween said pin sidewalls and said slot inner walls;

d. a first projection (61, 60, 47, 43, 42, 34) filling a portion of saidgap extending from said first and second pin sidewalls and filling aportion of said gap extending from said second inner wall; saidprojections providing longitudinal stability for said pin as it isengaged by the device under test and allowing air to provide adielectric around said projections in said gap.

There is also disclosed an apparatus wherein housing includes tubularelastomeric resilient element and wherein said pin includes an arcuaterecess for receiving a portion of said resilient element and whereinsaid projection extends from said pin sidewalls and encompasses at leasta portion of said resilient element; and further including a stabilizerprojection.

There is also disclosed a method of controlling the impedance of anintegrated circuit test housing for testing a device under test, thehousing having upper and lower surfaces, a first surface approachable byan integrated circuit device under test (12) to be tested and a secondsurface proximate the load board; a slot extending through said housingfrom the first surface to the second surface, said slot includingparallel spaced apart opposing first and second inner walls therebydefining a space between said sidewall; a contact pin having first andsecond sidewalls and being slideably receivable in said slot, said pinhaving a first end engageable by the lead and a second end in engagementwith the terminal, said pin filling only a portion of said slot therebyleaving a gap between said pin sidewalls and said slot inner walls;having any or all of the following steps:

forming a first projection filling a portion of said gap adjacent saidfirst inner wall and a second projection filling a portion of said gapadjacent said second inner wall; allowing air to fill spaces around saidprojections to provide a dielectric around said projections in said gap.

There is also disclosed a method wherein said step of forming first andsecond projections includes forming a projection extending from each ofsaid inner walls.

There is also disclosed a method wherein said step of forming first andsecond projections includes forming a projection extending from eachsidewall of said pin.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is side plan sectional view of a device under test (DUT) in ahousing with pins.

FIG. 2 is side perspective view of FIG. 1 with portions broken away anda close up of some pins.

FIG. 2A is a bottom plan schematic view of a housing with portionsbroken away showing pin/contact configuration with a wider base togetherwith a housing slot that is wide at the bottom and narrow at the top.The combination of housing and contact geometry produces air gapsbetween the contacts.

FIG. 2B is a side sectional view of a housing with pin removed. Thisview also shows a portion of the housing material between pins cut awayto improve the dielectric constant of the material between the pins.

FIG. 2C is a side sectional view of a housing opposite of FIG. 2B ofstandard housing geometry.

FIG. 3 is a perspective view of FIG. 2B.

FIG. 4 is a view like FIG. 3 but with multiple pin slots shown in thehousing.

FIG. 5A is a side perspective view of a pin with projections. Aconfiguration like this can be used to position two pins next to eachother (with no housing webbing/wall in between). The projections arepositioned differently on each side of the pin so that the projectionsdon't touch each other and cause a problem when the contacts areinstalled against each other and then actuated during IC testing. Theprojections can be any shape that is convenient to manufacture. They donot have to be round.

FIG. 5B is the other side of FIG. 5A.

FIG. 5C is a top view of FIG. 5A but with closer projections on oneside.

FIG. 5D is a front view of FIG. 5A.

FIG. 5E is a side view of FIG. 5A.

FIG. 5F is a rear view of FIG. 5A

FIG. 5G is bottom view of FIG. 5A but with closer projections on oneside like in FIG. 5C.

FIG. 6 is a side plan view of the pin in FIG. 5A in a housing.

FIG. 7 is a top view of FIG. 6.

FIG. 8 is a top view of FIG. 6 with portions of the housing broken away.

FIG. 9 is a perspective view of FIG. 6.

FIG. 10 is a perspective view of a pin like FIG. 5A except withtruncated conical/domed projections.

FIG. 11 is a rear perspective view of FIG. 10.

FIG. 12 is a side plan view of FIG. 10.

FIG. 13 is a bottom plan view of 12 showing projections on one sidebeing closer to each other than projections on the other side, i.e.asymmetrical.

FIG. 14 is a view like FIG. 11 except with the projections beingcylindrical.

FIG. 15A is a side plan view of a section of the housing showing a pinwith two elastomers.

FIG. 15B is the other side view of FIG. 15A.

FIG. 16 is a perspective view with portions broken away of oneembodiment of the pin with a wide foot/base.

FIG. 17 is perspective view of the subject matter in FIG. 16.

FIG. 17A is a side perspective view of the recess 31. Note that thehousing in this figure does not touch the load board but is elevated orfloating above it. This further increases the air dielectric.

FIG. 18 is a bottom perspective view of the subject matter of FIG. 16.This view shows on the right side two areas of the housing cut away(cross hatch region) so that the narrow part of the contact can be seen.

FIG. 19 is a bottom perspective view of a housing and DUT with portionsbroken away.

FIG. 20 is a close up perspective view of a portion of FIG. 19.

FIG. 21 is a bottom perspective view of a housing with pins removed.

FIG. 22 is a close up view of a portion of FIG. 21.

FIG. 23 is a side view sectional of a pin in a housing.

FIG. 24 is a perspective view of FIG. 22.

FIG. 25 is a side section view of FIG. 23 with the pin deflected by aDUT.

FIG. 26 is a view like FIG. 25 before pin deflection.

FIG. 27 is a sectional perspective view of a housing havinglands/projections into the pin slot.

FIG. 28 is a schematic view of a housing with portions broken away.

FIG. 29 is a top view of a slot having lands/projections like FIG. 27.

FIG. 30 is a view like FIG. 27 with a pin in place.

FIG. 31 is a bottom view of a portion of a housing with slots.

FIG. 32 is a bottom view of one of the slots in FIG. 31. The inner linescentral in this figure show that the top part is narrower than thebottom part in accordance with that embodiment which has a wide/narrowpin.

FIG. 33 is a bottom perspective view of a portion of FIG. 31.

FIG. 34 is view like FIG. 33 with a pin in place.

FIG. 35 is a close up perspective view of a pin in a housing with a widefoot/base.

FIG. 36 is a perspective view of a plurality of pins and elastomers.

FIG. 37 is a perspective view of a pair of pins of two types.

FIG. 38 is another perspective view of the pins in FIG. 37.

FIG. 40 is another perspective view of the pins in FIG. 37.

FIG. 41 is a front view of the pins in FIG. 37.

FIG. 42 is a top plan view of a pin in a housing slot with portionsbroken away. The broken lines denote that the housing would normally bemuch larger with more pins and slots in it.

FIG. 43 is a bottom plan view of FIG. 42 with a slot havingprojections/lands. This shows a wide foot style (i.e. thicker lowerportion of the pin) contact in a housing. The foot of the pin is at thebottom of the view. The thinner part of the pin is obscured by the frontelastomer.

FIG. 44 is view of like FIG. 43. This view is a sectional view with 14being the load board. The view is from the center of the housing lookingtoward the outside.

FIG. 45 is a side plan sectional view of FIG. 42 similar to FIG. 44.

FIG. 46 is a perspective view of a pin and housing with portions brokenaway similar to FIG. 17 but an alternate embodiment.

FIG. 47 is a front sectional view of a housing.

FIG. 48 is a close up view of a portion of FIG. 47.

FIG. 49A is a perspective view of an alternate pin embodiment with adiagonal projection/land on one or both sides.

FIG. 49B is a view like FIG. 49A but the other side.

FIG. 49C is a bottom view of FIG. 49A.

FIG. 49D is a front view of FIG. 49A.

FIG. 49E is a side plan view of FIG. 49A.

FIG. 49F is a rear view of FIG. 49A.

FIG. 49G is a top view of FIG. 49A

FIG. 50 is a side perspective view with portions broken away of analternative embodiment of a pin with a shaped projection/land.

FIG. 51 is a side perspective view of the pin in FIG. 50.

FIG. 52 is a bottom perspective view of the pin in FIG. 50.

FIG. 53 is a side plan view of the pin in FIG. 50.

FIG. 54 is a front sectional view of a portion of FIG. 50.

FIG. 55A is a top plan view of a housing with pins.

FIG. 55B is a side plan view of a housing with pins.

FIG. 55C is a bottom plan view of a housing with pins.

FIG. 55D is a side sectional view of a housing with pins shown.

FIG. 56 is a side sectional view of a pin from FIG. 55D in anuncompressed state.

FIG. 57 is a side sectional view of a pin from FIG. 55D in a deflectedstate.

FIG. 58 is a top plan view of a slot from FIG. 56.

FIG. 59 is a bottom plan view of a slot from FIG. 56.

FIG. 60 is a bottom perspective view of a housing with pins and portionsbroken away.

FIG. 61 is a close up perspective view of a pin in a housing from FIG.60 in an uncompressed state.

FIG. 62 is a bottom perspective view of a housing with pins and portionsbroken away.

FIG. 63 is a close up perspective view of a pin from FIG. 60 in adeflected state.

FIG. 64 is a side perspective view of a housing having a plurality ofprojections.

FIG. 65 is a top plan view of the slot/housing in FIG. 64.

DETAILED DESCRIPTION

This disclosure is directed to a structure and method to make a betterperforming contact by making load board interface and maintaining orchanging the housing, i.e. test contactor assembly, impedance to besuitable for the chip testing desired.

There are multiple ways to accomplish this shown in the drawings anddescribed below.

One solution is making the pin contact wide enough to spread outstresses on the load board (i.e. bottom of pin) which reduces wear onthe expensive load board. Simultaneously it allows the rest of contactto be thinner to improve impedance matching and mechanical robustness byhaving a thinner tipped contact hitting a small pad I/O on device.

Also, by making the upper portion of the contact thinner, there is agreater chance of solid electrical contact with a pad/ball of the deviceunder test (DUT). The contact/pin preferably includes a thin portionrunning most of the length of contact makes the contact also lighter,thus reducing the forces needed to be applied during the insertion ofDUT into the housing/contactor, thus improving the life of all parts ofsystem.

Having the transition from small width top portion of contact to largerwidth bottom portion below the top of the front elastomer results in thebest tradeoff between mechanical robustness and electrical performance.The transition from thinner top portion of contact can be a straightedge, which is easier to machine or chamfer to reduce reflections of theRF signals.

The housing slot changes widths based on contact width to make surecontact pin can hit the smallest of DUT pads. The location of the “step”(i.e. transition from thick to thin) in the housing can be optimized toalign the contact pin accurately, but also to provide an improvedeffective dielectric constant between adjacent contact pins through theuse of an air gap between the contact pin and the housing slot.

It is possible to add non-conductive bumps on the sidewalls of thepin/contacts allow a significant air gap all around the contacts. Havingair between the contacts improves their impedance significantly whencompared to most rigid structural materials that can be used to make acontactor/housing. The disadvantage of this is that it is difficult tomanufacture non-conductive bumps on the sides of the contacts.

FIG. 1 is side plan sectional view of test system 10 with ahousing/contactor 14 and device under test (DUT) 12 in a housing.Pins/contacts 20 with elastomer bias 22 elements and a load board 24.Bias elements 22 can be tubular, circular or spherical elastomers orother forms of spring bias. The pins include an arcuate region toreceive a portion of the elastomer thereby biasing the pin.

FIG. 2 is a close up view with the elastomers removed. Pin 20 has alower part 30 which engaged the load board and upper part 32 whichengaged the DUT. The lower part 30 is thicker than the upper part 32with a transitional step 34 therebetween. This step can also be a slopedtaper. In this case 12 does not actually show a DUT. Rather, it is aplatform in the center of the housing that is used to prevent the DUTfrom compressing/deflecting the pins too far. The DUT is not shown inthis view from the top because it would cover the tops of the pins,hiding them from view. This platform in combination with thepocket/recess in the top of the housing around the contact pins createsan air gap between the contacts when they are compressed.

FIG. 2A is a top plan schematic view of a housing with portions brokenaway.

FIG. 2B is a side sectional view of a housing with pin removed. FIG. 2Bshows a portion of the housing wall between pins cut away (i.e. creatinga recess) to improve the dielectric constant of the material between thepins. With the cut out there is more air between the pins, so theeffective dielectric is improved.

FIG. 2C is a side sectional view of a housing opposite of FIG. 2B (showsa housing without the wall removed vs. 2B that has part of the wallremoved).

FIG. 3 is a perspective view of FIG. 2B.

FIG. 4 is a view like FIG. 3 but with multiple pin slots 40 shown in thehousing.

FIGS. 5A, 5B, 5C, 5D, 5E, 5F and 5G show one embodiment of pin 20 havingprojections or lands 42 on either or both sidewalls of the pins. Theprojections 42 are spaced apart along the sidewall. Notice that theprojections can be symmetric on both sides (i.e. in the same location onboth sides, or preferably asymmetrically). FIG. 5G is an asymmetricalexample, where one side has the projections closer together and theother farther apart on the sidewall. It is useful to have theprojections asymmetrically positioned in order that the pin be spacedfrom the housing slot sidewall on different points for stability and toresist torque forces which occur when a DUT engages the pin. This allowsfor pins to be used in very small pitch (spacing between pins) housing.A configuration like this (asymmetric projections) can be used toposition two pins next to each other (with no housing webbing/wall inbetween). The projections are positioned differently on each side of thepin so that the projections don't touch each other and cause a problemwhen the contacts are installed against each other and then actuatedduring IC testing. This configuration allows the pins to be extremelyclose together, because there is no need for a thin housing web/wall inbetween pins.

The shape of the projections can be varied at their base and theirentire profile. In this case, the projections are dome or hemisphericalshaped.

FIG. 6 is a side plan view of the pin in FIG. 5A in a housing.

FIG. 7 is a top view of slot 40 showing the gap 48 which is filled bythe pin 14 and projections 42. The gap is not completely transverselyfilled however, as the pin must be free to slide in the slot.

FIG. 10 is a perspective view of a pin like FIG. 5A except withtruncated conical/domed projections having a flat top surface 50 but atruncated conical base portion.

FIG. 14 is a view like FIG. 11 except the pin 20 has projections whichare cylindrical with a flat top.

FIGS. 15A and 15B are side plan views of a section of the housingshowing a pin 20 with a two elastomers 22 in a housing 14. 15A shows ahousing slot that is the same width top to bottom. 15B shows a housingslot with a wider bottom portion and narrower top portion.

FIGS. 16 and 17 are a perspective of pin 20 with upper pin portion 30,lower pin portion 32 and the step transition 34 shown in greater detail.The transition can be stepwise, sloped (arcuate) or other shape asdesired. The position of the transition from thick (wide) to thin(narrow) can be varied. It is desirable that the thickened part of thepin be surrounding at least one-half or one-third or one quarter of theelastomer to minimize the shearing force of the pin the elastomer (asmuch as possible elastomer surface contact is preferred), but thiscompetes with the benefit of the largest amount of thin pin area aspossible to lower or reduce the dielectric effect. It is also desirableto have enough thick pin area to resist twisting/torqueing of the pin inresponse to its collision with the DUT. Furthermore, the thickened areaat the base of lower pin part 32 spreads force over a larger area of theload board, which in turn reduces load board wear. The thickened portion32 shown in FIGS. 16 and 17 is high enough up the pin to surround aboutone quarter to one third of the elastomer and about one quarter of theentire pin. Note that the thickened (wide) portion can be thickened onlyon one sidewall, or both as shown. FIGS. 17 and 17A also illustrate afeature to control impedance. The top of housing 14 has traditionallybeen flat, but as shown in FIGS. 2, 17, 17A and others, the top surfacemay include a recess 31 which exposes more of pin 20 toward their tip.Since air is the best dielectric, recessing the top surface adjacent thepins tips can improve performance. The remainder of the top surface isnot recessed so that the DUT depth is properly aligned. FIG. 17A alsoshows material removed at the bottom of the housing between theelastomer slots to improve the dielectric between the lower part of thecontact pins.

The contact pins are adjacent each other without intervening housingwalls and their projections preferably are located on the sidewalls atpositions so that projections are never in direct contact with eachother even when the pins are deflected. Thus the preferred placement isasymmetrical.

FIG. 18 is a bottom perspective view of a housing showing slots 40 forpins. This view shows on the right side two areas of the housing cutaway (cross hatch) so that the narrow part of the contact can be seen.

FIG. 19 is a bottom perspective view of a housing and DUT with portionsbroken away and FIG. 20 is a close up perspective view.

FIG. 21 is a bottom perspective view of a housing with pins removed.This view has vertical beams added to the housing webbing between pins.These beams could also be horizontal or another angle.

FIG. 22 is a close up view with slots 40.

FIG. 23 is a side view sectional of a prior art contact pin in a housingwith elastomers.

FIG. 24 is a perspective view of the subject of FIGS. 21 and 22 withcontact pins shown. Beams are shown as part of the housing to give anair gap between pins.

FIG. 25 is a side section view of a pin in the housing with the pindeflected downwardly by a DUT. FIG. 26 is a view like FIG. 25 before pindeflection.

FIG. 27 is a sectional perspective view of a housing with an alternateembodiment. Instead (or in addition) to having lands/projections on thepin sidewalls, the housing slots 40 can have projections 60 in the spacedefined by the slot. The projections can extend fully the length of theslot or can by short segments placed at different locations in the slot.The number of projections can be two on each sidewall, as shown, or 1 oneach side, or 3 or 4 or more on each side. The number on each side maybe the same or unequal. The location on the respective sidewalls may besymmetrical/mirror image, as shown or asymmetrical, with the projectionsnot directly opposing but offset from the facing projection. Theprojections can be vertically oriented as shown, or they can behorizontal or at another angle. The projections do not need to bestraight. They can be curved.

FIG. 28 is a schematic view of a housing with portions broken away withFIG. 29 is a top view of a slot having lands/projections described aboveand FIG. 30 shows a perspective view. FIG. 28 shows a housing with someslots that are prior art (wider slots) and other slots that haveprojections as described in this document.

The projections 60 can be flat as shown, or like the projections on thepins, conical, cylindrical or other shapes so long as they provide standoffs from the sidewall and maximize the dielectric air space.

FIG. 31 is a bottom view of a portion of a housing with slots. FIG. 32is a bottom view of one of the slots in FIG. 31 without a pin in place.In this embodiment the slot 40 is narrower at the top than at the bottomwhich is consistent with the pin which is wider at the bottom andnarrower at the top. The sidewall of the slot therefore may havelikewise a step of sloped graduation from wide to narrow. The width ofthe slot is just greater than the thickness/width of the correspondingpin or pin portion. That means that the slot allows for the pin to slidewithin the slot with little or no friction. FIG. 33 is a bottomperspective view of a portion of FIG. 31 without pins. FIG. 34 is viewlike FIG. 33 with pins 20 in place.

FIG. 35 is a close up perspective view of a pin in a housing with a widefoot/base 32. In this case, the widened portion 32 is substantiallylimited to the portion of the pin which sits under lower elastomer 42and extending to tail end 54.

FIG. 36 is a perspective view of a plurality of pins 20 and elastomers22.

FIGS. 37-41 provide a comparison of a full thickness pin 21 with themulti-thickness pin 22. Pin 21 in this case has a narrow tip which isadvantageous, but pin 22 is inherently narrow so it does not require asecond step.

FIGS. 42-45 show a pin in a housing slot with a pin and projectionswhich could either be on the pin (40) or slot (60).

FIG. 46 is alternative embodiment similar to FIG. 17. In this embodimentthe thickened portion 32 is defined as at a horizontal line 34, belowwhich the remainder of the pin is thicker than the upper portion 30.

FIG. 47 is a front sectional view of a housing and slots with pins. FIG.48 is a close up view of a portion of FIG. 47 with pins shown.

FIGS. 49A, 49B, 49C, 49D, 49E, 49F and 49G are views of an alternate pinembodiment with a diagonal projection/land on one or both sides.

In these embodiments, pin 20 had a projection area or land 43 whichextends substantially the length of the pin and extends or is applieddiagonally across the sidewall or both sidewalls. As in case ofprotections 42, these projections can be integral to the pin or appliedto the pin as an add on element. In the case of an applique, thematerial may be non-conductive, such as Torlon®. A non-conductor, orconductor coated with an insulating material is desirable because thehousing 14 may be metal for certain applications. In this embodiment,land 43 extends adjacent the upper tip (though it does not have to reachthat tip) and then diagonally across the pin sidewall to the lower footof the pin. Again, it does not need to be coexistent with the foot, butit would be desirable because it will spread forces over a greater area,minimizing load board wear. The land may be on both or just one sidewallof the pin.

FIGS. 50, 51 and 52 are perspective views of an alternative embodimentwhich combine features from previously mentioned embodiments. In thisembodiment, the land 43 extends from adjacent the upper to, follows adownward path, such as serpentine, s-shaped, toward the foot but becomespart of the pin which has an arcuate recess for the elastomer (notshown) and then becomes part of the lower portion and foot of the pin.In this embodiment, the tail/foot portion of the pin (in contact withthe load board) is interposed between the elastomer and the load board.The elastomer applies a downward pressure on the tail. The projection 43provides a wider pin foot for the load board contact, but much of therest of the pin has no projection. This provides more space for an airdielectric. This structure therefore does not interfere with thegeometric of the pin tip which engaged the DUT but provides boarderengagement with the elastomer, thus reducing the risk of shear and thenbroadens the foot portion of the pin, likewise reducing pressure andwear on the load board. The land may be on one or both sidewalls of thepin. Also optionally included on this pin is an arcuate land 47 which islocated on the edge opposite of land 43. This land 47 is intended as astabilizer for the pin since it provides a second point of guidancebetween the inner walls of the slot and therefore improves the pinalignment with the slot. This second land 47 is flush with theperipheral edge of the pin and preferably has an arcuate rear edge andpreferably projects as much as land 43 from the pin surface. FIG. 54 isa front sectional view of a portion of FIG. 50.

FIGS. 55A, 55B, 55C and 55D show the pin of FIG. 50 in a housingenvironment.

FIG. 56 is a side sectional view of a pin from FIG. 55D in anuncompressed state, before insertion of a DUT. FIG. 57 is a sidesectional view of a pin from FIG. 55D in a deflected state after DUTinsertion.

FIG. 60 is a bottom perspective view of a housing with pins and portionsbroken away with a close up view in FIG. 61, with the pin 20 in anuncompressed state.

FIGS. 62-63 are bottom perspective views of a housing with pins andportions broken away in a deflected state.

FIG. 64 is a side perspective view of a housing having a plurality ofprojections 61 which provide the same function as projections 60 in FIG.27 of keeping the pin spaced from the housing wall by providing maximumair dielectric spacing. The projections 61 can be symmetrically orasymmetrically placed on the opposing sidewalls of the slot 40. Theprojections as shown are cylindrical but may be conical, truncated, orother shapes so long as they provide the required standoff. Conical ordomed/hemispherical projections are shown in FIG. 65.

The description of the invention and its applications as set forthherein is illustrative and is not intended to limit the scope of theinvention. Variations and modifications of the embodiments disclosedherein are possible and practical alternatives to and equivalents of thevarious elements of the embodiments would be understood to those ofordinary skill in the art upon study of this patent document. These andother variations and modifications of the embodiments disclosed hereinmay be made without departing from the scope and spirit of theinvention.

1. An apparatus for electrically connecting a lead of an integratedcircuit (12) device to be tested to a corresponding terminal of a loadboard (24) at a test site, comprising: a. a housing (14) having upperand lower surfaces, a first surface approachable by an integratedcircuit device under test (12) to be tested and a second surfaceproximate the load board; b. a slot extending through said housing fromthe first surface to the second surface, said slot including parallelspaced apart opposing first and second inner walls thereby defining aspace between said sidewalls; c. a contact pin (20) having first andsecond sidewalls and being slideably receivable in said slot (40), saidpin having a first end engagable by the lead and a second end inengagement with the terminal, said pin filling only a portion of saidslot thereby leaving a gap between said pin sidewalls and said slotinner walls; d. a first projection (61, 60, 47, 42, 43, 34) filling aportion of said gap adjacent said first inner wall and a secondprojection filling a portion of said gap adjacent said second innerwall; said projections providing longitudinal stability for said pin asit is engaged by the device under test and allowing air to provide adielectric around said projections in said gap.
 2. The apparatus ofclaim 1 wherein said projections extend from said pin toward said innerwall.
 3. The apparatus of claim 1 wherein housing includes tubularelastomeric resilient element and wherein said pin includes an arcuaterecess for receiving a portion of said resilient element and whereinsaid projection extends from said pin sidewalls and encompasses at leasta portion of said resilient element.
 4. The apparatus of claim 1 whereinsaid projections are a plurality of lands spaced across the pinsidewall.
 5. The apparatus of claim 4 wherein said lands areasymmetrically placed on said first side wall relative to said secondsidewall.
 6. The apparatus of claim 1 wherein said projections are aplurality of lands spaced across the pin inner wall of said slots. 7.The apparatus of claim 1 wherein said projections extend from one orboth of said inner walls of said slot toward said pin.
 8. The apparatusof claim 1 wherein said pin includes a top and bottom ends and whereinsaid projections extend adjacent said top and bottom ends.
 9. Theapparatus of claim 1 wherein said pin includes a top and bottom ends andwherein said projections extend between said top and bottom ends along acurved path.
 10. The apparatus of claim 1 wherein said pin includes atop and bottom ends and wherein said projections extend between said topand bottom ends along a curved path and including a land portionpartially surrounding said resilient member.
 11. The apparatus of claim1 wherein said pin includes a top and bottom ends and wherein saidprojections extend between said top and bottom ends along a diagonalpath.
 12. The apparatus of claim 1 wherein said housing (14) includes atop surface having said slots (40) and wherein said surface adjacentsaid slots is recessed (31) thereby exposing a portion of said pins toair.
 13. The apparatus of claim 1 wherein said contact pin includes anupper portion of predetermined thickness and a lower portion ofthickness greater than said predetermined thickness and wherein saidslot had upper and lower spaced apart sidewalls, said upper sidewallsbeing spaced to just accommodate said upper portion of said pin portionand said lower sidewalls being spaced apart to just accommodate saidlower pin portion, so that said pin may slide within said sidewalls. 14.An apparatus for electrically connecting a lead of an integrated circuit(12) device to be tested to a corresponding terminal of a load board(24) at a test site, comprising: a. a housing (14) having upper andlower surfaces, a first surface approachable by an integrated circuitdevice under test (12) to be tested and a second surface proximate theload board; b. a slot extending through said housing from the firstsurface to the second surface, said slot including parallel spaced apartopposing first and second inner walls thereby defining a space betweensaid sidewall; c. a contact pin (20) having first and second sidewallsand being slideably receivable in said slot (40), said pin having afirst end engagable by the lead and a second end in engagement with theterminal, said pin filling only a portion of said slot thereby leaving agap between said pin sidewalls and said slot inner walls; d. a firstprojection (61, 60, 47, 43, 42, 34) filling a portion of said gapextending from said first inner wall and a second projection filling aportion of said gap extending from said second inner wall; saidprojections providing longitudinal stability for said pin as it isengaged by the device under test and allowing air to provide adielectric around said projections in said gap.
 15. The apparatus ofclaim 14 wherein said projections are lands having planar distalsurfaces.
 16. The apparatus of claim 14 wherein said projections areconical having planar distal surfaces.
 17. The apparatus of claim 14wherein said projections are spherical.
 18. The apparatus of claim 14wherein said projections are cylindrical and having planar distalsurfaces.
 19. An apparatus for electrically connecting a lead of anintegrated circuit (12) device to be tested to a corresponding terminalof a load board (24) at a test site, comprising: a. a housing (14)having upper and lower surfaces, a first surface approachable by anintegrated circuit device under test (12) to be tested and a secondsurface proximate the load board; b. a slot extending through saidhousing from the first surface to the second surface, said slotincluding parallel spaced apart opposing first and second inner wallsthereby defining a space between said sidewalls; c. a contact pin (20)having first and second sidewalls and being slideably receivable in saidslot (40), said pin having a first end engagable by the lead and asecond end in engagement with the terminal, said pin filling only aportion of said slot thereby leaving a gap between said pin sidewallsand said slot inner walls; d. a first projection (61, 60, 47, 43, 42,34) filling a portion of said gap extending from said first and secondpin sidewalls and filling a portion of said gap extending from saidsecond inner wall; said projections providing longitudinal stability forsaid pin as it is engaged by the device under test and allowing air toprovide a dielectric around said projections in said gap.
 20. Theapparatus of claim 17 wherein housing includes tubular elastomericresilient element and wherein said pin includes an arcuate recess forreceiving a portion of said resilient element and wherein saidprojection extends from said pin sidewalls and encompasses at least aportion of said resilient element; and further including a stabilizerprojection. 21-23. (canceled)